Fabrication of Novel Ferromagnetic Materials by Modification of Surface of Iron Nanoparticles

Abstract

In order to fabricate the high performance permanent magnet, we had prepared the following materials as the precursor of nanocomposite magnet by using core-shell structure with Fe phase as soft phase and ε-Fe₂O₃ phase as hard phase. In order to prepare air-stable metallic Fe nanoparticles, iron-oxide nanoparticles as precursors were reduced in a hydrogen atmosphere and then their surfaces were oxidized under low concentration of oxygen. To obtain Fe₂O₃ phase, we treated iron oxide nanoparticles with silica shell at several temperature. The size of magnetic nanoparticles affects their magnetism. We had also controlled the particle size and crystal structure.